Continued: AGING AMERICA: People skeptical of research to extend lifespan; most don't want to reach 120

The next step is to find medications that might somehow switch on those protective pathways, rather than drastic dieting or gene manipulation. A number of candidates have worked in animals. Just last month, NIA researchers reported that a low dose of the diabetes drug metformin improved the health and longevity of middle-aged mice.

No anti-aging pill is ready to try in people yet. Aging specialists say for now, common-sense is the best medicine: Eat a healthy diet, maintain a healthy weight and exercise.

Asked about the poll, graduate student Katie Lebling, 24, of Washington said good health is key to how long she'd like to live: "It depends on how happy I am, if I was able to move or if I'm just sitting in a rocking chair."

If good health was a given, others wouldn't mind living to 120. "I'm curious to see how things now would be then," said John Gold, 38, a San Francisco software engineer.

The Pew Research Center's Religion & Public Life Project survey was conducted from March 21 to April 8, 2013. The nationally representative survey involved interviews, conducted on cell phones and landlines, with 2,012 adults. It has a margin of error of plus or minus 2.9 percentage points.

EDITOR'S NOTE _ Aging America is a joint AP-APME project examining the aging of the baby boomers and the impact that this so-called silver tsunami will have on the communities in which they live.